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Wang X, O'Connor J, Zheng X, Wang Y, Kiat Y. Earliest evidence of avian primary feather moult. Biol Lett 2024; 20:20240106. [PMID: 38955226 DOI: 10.1098/rsbl.2024.0106] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2024] [Accepted: 05/22/2024] [Indexed: 07/04/2024] Open
Abstract
Feather moulting is a crucial process in the avian life cycle, which evolved to maintain plumage functionality. However, moulting involves both energetic and functional costs. During moulting, plumage function temporarily decreases between the shedding of old feathers and the full growth of new ones. In flying taxa, a gradual and sequential replacement of flight feathers evolved to maintain aerodynamic capabilities during the moulting period. Little is known about the moult strategies of non-avian pennaraptoran dinosaurs and stem birds, before the emergence of crown lineage. Here, we report on two Early Cretaceous pygostylian birds from the Yixian Formation (125 mya), probably referable to Confuciusornithiformes, exhibiting morphological characteristics that suggest a gradual and sequential moult of wing flight feathers. Short primary feathers interpreted as immature are symmetrically present on both wings, as is typical among extant flying birds. Our survey of the enormous collection of the Tianyu Museum confirms previous findings that evidence of active moult in non-neornithine pennaraptorans is rare and likely indicates a moult cycle greater than one year. Documenting moult in Mesozoic feathered dinosaurs is critical for understanding their ecology, locomotor ability and the evolution of this important life-history process in birds.
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Affiliation(s)
- Xiaoli Wang
- Institute of Geology and Paleontology, Linyi University, Linyi, Shandong 276005, China
- Tianyu Natural History Museum of Shandong, Pingyi, Shandong 273300, China
- College of Earth Science and Engineering, Shandong University of Science and Technology, Qingdao, Shandong 266590, China
| | - Jingmai O'Connor
- Negaunee Integrative Research Center, Field Museum of Natural History, Chicago, IL 60605, USA
| | - Xiaoting Zheng
- Tianyu Natural History Museum of Shandong, Pingyi, Shandong 273300, China
| | - Yan Wang
- Institute of Geology and Paleontology, Linyi University, Linyi, Shandong 276005, China
- Tianyu Natural History Museum of Shandong, Pingyi, Shandong 273300, China
| | - Yosef Kiat
- Negaunee Integrative Research Center, Field Museum of Natural History, Chicago, IL 60605, USA
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Wang S, Chang WL, Zhang Q, Ma M, Yang F, Zhuo D, Hans HIC, Yang R, Wu P, Habib M, Juan WT, Chuong CM. Variations of Mesozoic feathers: Insights from the morphogenesis of extant feather rachises. Evolution 2020; 74:2121-2133. [PMID: 32614075 DOI: 10.1111/evo.14051] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2019] [Revised: 06/21/2020] [Accepted: 06/27/2020] [Indexed: 12/14/2022]
Abstract
The rachises of extant feathers, composed of dense cortex and spongy internal medulla, are flexible and light, yet stiff enough to withstand the load required for flight, among other functions. Incomplete knowledge of early feathers prevents a full understanding of how cylindrical rachises have evolved. Bizarre feathers with unusually wide and flattened rachises, known as "rachis-dominated feathers" (RDFs), have been observed in fossil nonavian and avian theropods. Newly discovered RDFs embedded in early Late Cretaceous Burmese ambers (about 99 million year ago) suggest the unusually wide and flattened rachises mainly consist of a dorsal cortex, lacking a medulla and a ventral cortex. Coupled with findings on extant feather morphogenesis, known fossil RDFs were categorized into three morphotypes based on their rachidial configurations. For each morphotype, potential developmental scenarios were depicted by referring to the rachidial development in chickens, and relative stiffness of each morphotype was estimated through functional simulations. The results suggest rachises of RDFs are developmentally equivalent to a variety of immature stages of cylindrical rachises. Similar rachidial morphotypes documented in extant penguins suggest that the RDFs are not unique to Mesozoic theropods, although they are likely to have evolved independently in extant penguins.
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Affiliation(s)
- Shuo Wang
- Department of Pathology, Keck School of Medicine, University of Southern California, Los Angeles, California, 90033
| | - Wei-Ling Chang
- Integrative Stem Cell Center, China Medical University Hospital, Taichung, 40447, Taiwan
| | - Qiyue Zhang
- College of Life Sciences, Nankai University, Tianjin, 300071, China
| | - Menglu Ma
- Laboratory of Vertebrate Evolution, College of Life Sciences, Capital Normal University, Beijing, 100048, China
| | - Feng Yang
- Beijing Advanced Innovation Center for Imaging Technology, Capital Normal University, Beijing, 100048, China
| | - De Zhuo
- Beijing Xiachong Amber Museum, Beijing, 100083, China
| | - Harn I-Chen Hans
- Department of Pathology, Keck School of Medicine, University of Southern California, Los Angeles, California, 90033
- International Research Center of Wound Repair and Regeneration, National Cheng Kung University, Tainan, 70101, Taiwan
| | - Rui Yang
- Laboratory of Vertebrate Evolution, College of Life Sciences, Capital Normal University, Beijing, 100048, China
| | - Ping Wu
- Department of Pathology, Keck School of Medicine, University of Southern California, Los Angeles, California, 90033
| | - Michael Habib
- Department of Pathology, Keck School of Medicine, University of Southern California, Los Angeles, California, 90033
- Los Angeles County Museum of Natural History, Los Angeles, California, 90007
| | - Wen-Tau Juan
- Integrative Stem Cell Center, China Medical University Hospital, Taichung, 40447, Taiwan
- Department of Biomedical Imaging and Radiological Science, China Medical University, Taichung, 40402, Taiwan
| | - Cheng-Ming Chuong
- Department of Pathology, Keck School of Medicine, University of Southern California, Los Angeles, California, 90033
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